Once again, this month, we are bombarded with information in journals about diabetes. Here, we will bring you a review of abstracts on the subject so that you will be able to better understand the state of the art in research and understand diabetes better. Again, if you have specific topics that you want included, please let us know and we'll be on the lookout for articles on that subject. This month we look at articles on simple therapy changes in type 2 diabetes, type 2 and psychomotor slowing in middle age, hypertension and diabetes, long-term effects of increased fiber in blood glucose control, clinical characteristics of type 1 diabetics with and without severe hypoglycemia, and finally the hormone that may be needed by diabetics to impede complications.
Before we begin, here are two short takes from recent JAMA journals. The Nov.9th volume has a medical news and perspective article that shows no link between vaccination against hepatitis B virus and an increased risk for type 1 diabetes in children. To read about this look at page 2307. The Nov.1,2000 volume has an article about the treatment of diabetic polyneuropathy with rhNGF on page 2215 by Apfel, SC, MD et al. This is an important finding because unlike previous phase 2 trials, this phase 3 clinical trial failed to demonstrate a beneficial effect of rhNGF on diabetic polyneuropathy.
First we look at an article from the Western Journal of Medicine 2000; 173:175-179 which reports that a substantial number of type 2 diabetics could achieve better control with simple adjustment in their pharmacologic therapy. The authors examined electronic pharmacy data for 5061 members of a large HMO with type 2 diabetes. These people were assigned to one of four groups: users of insulin, alone or in combination with metformin or sulfonylureas (26.6%): users of metformin, alone or in combination with sulfonylureas (15.3%); users of sulfonylureas (40.5%), and subjects not taking any antidiabetic drug (17.6%). Within these groups, the patients were further divided into those with HbA1c less than and more than 8%.
The researchers observed some demographic patterns that could predict at-risk populations. They noted that older type 2 diabetic patients who had the disease for a shorter period of time had better control of the disease than younger people who had the disease for a longer period of time. They also found that women control diabetes better than men. These findings were true across all therapeutic categories.
The researchers found that 31% of the subjects had a HbA1c of over 8%. They found that 55.3% of those who had not achieved glycemic control on insulin or metformin could have better control merely by increasing their doses. They also noted that many subjects who were failing on sulfonylurea therapy were continued on this therapy rather than being switched to combination therapy or having insulin added.
Diabetes Care 2000; 23: 1486-1493 had an article about Type 2 diabetes linked to psychomotor slowing in middle-aged adults by C.M. Ryan, M.D. and M.O. Geckle. The researchers examined several aspects of cognitive function in 50 middle-aged subjects (mean 50.8 years) with type 2 diabetes and 50 diabetes-free matched controls. Performance on tests of three of the four cognitive domains - learning, memory, and problem solving - were unaffected by type 2 diabetes. This contrasts with many studies that examine adults over 65 years of age which indicate that verbal learning and memory problems are commonly associated with type 2 diabetes. The researchers speculated that the interaction of age and glycemic control may affect these cognitive domains and suggest further investigations. On the other hand, performance on psychomotor tests was significantly slower in diabetic patients. Also, of note was the fact that this slowing was independent of metabolic control and vibratory threshold.
This finding is consistent with prior studies with type 1 and type 2 adults and in children with type 1 diabetes. They conclude that the link between psychomotor slowing and diabetes is because of the link between mental slowing and chronic hyperglycemia which has been reported in older adults.
Hypertension and diabetes in Archives of Internal Medicine: 2000; 160;1585-1594 by P.C. Deedwaria, MD looks at the treatment of high-risk hypertensive patients with diabetes. The co-existence of hypertension and diabetes dramatically and synergistically increases the risk of microvascular and macrovascular complications, perhaps the most important among these being the increased risk of cardiovascular events in these patients, a fact that can be proven by the increased number of deaths attributed to cardiovascular-related diseases in diabetic patients aged 45-65 years of age. Recent guidelines from the Sixth Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure, which emphasized the importance of treating patients with hypertension and diabetes as if they already have target organ damage. Low blood pressure targets of 130/85 mm HG with an optimal goal of 120/80 mm HG can reduce the risk of events in hypertensive persons with diabetes, regardless of the pharmacological means used. However, there are physiologic and clinical rationale for renin angiotensin system blockade, with angiotensin-converting enzyme inhibition as the preferential therapy in these patients. In this regard, preliminary data with the new class of angiotensin ll receptor blockers suggest that these agents may offer benefits equivalent to those observed with angiotensin-converting enzyme inhibitors while offering better tolerance.
Diabetes Care 23: 1461-1466, 2000 has an article titled, Long-term dietary treatment with increased amounts of fiber-rich low-glycemic index natural foods improves blood glucose control and reduces the number of hypoglycemic events in type 1 diabetic patients by R.Giacco, MD et al. The researchers evaluated type 1 diabetics and the long-term feasibility of a high-fiber (HF) diet composed of natural foodstuffs and the efficacy of this diet in relation to blood glucose control and incidence of hypoglycemic episodes. The study was randomized with parallel groups and was part of a larger multicenter study on the effects acarbose on glucose control in diabetes. A total of 63 type 1 diabetic patients, age 28± 9 years, BMI 24± 0.6 kg/m2, after 4-week run-in period on their habitual diet, were randomized to either HF (n=32) or low-fiber (LF) diet (n=31) for 24 weeks. The two diets, composed exclusively of natural foodstuffs, were weight-maintaining, and aside from the fiber content, were similar for all nutrients. At the end of the run-in period and dietary treatment, fasting blood samples for the measurement of plasma cholesterol, HDL cholesterol, triglycerides, and HbA1c were collected. A daily glycemic profile was performed on a day in which the participants had consumed a standard menu representative of their treatment diet (HF or LF).
Of the 63 study subjects, 29 of the HF group (91%) and 25 in the LF (61%) group completed the study. Compared with the LF diet, the HF diet after 24 weeks decreased both mean daily blood glucose levels and the number of hypoglycemic events. When compliance to diet was taken into account, 83% of the subjects on the HF diet and 88% on the LF diet were compliant. In this subgroup, compared with the LF diet, the HF diet significantly reduces mean daily blood glucose concentration and the number of hypoglycemic events. The researchers concluded that in type 1 diabetic patients an HF diet is feasible in the long term, compared to a LF diet, and it improves glycemic control and reduces the number of hypoglycemic events.
Diabetes Care 23: 1467-1471, 2000 has an article titled Clinical characteristics of type 1 diabetic patients with and without severe hypoglycemia which investigated the frequency of severe hypoglycemic (SH) and hypoglycemic coma and tries to identify clinical and behavioral risk factors in a nonselected population of type 1 diabetic patients, written by E.W.M.T. er Braak, MD et al.
The study involved a retrospective clinical survey of 195 consecutive patients using a questionnaire addressing the frequency of SH and hypoglycemic coma during the previous year, general characteristics, behavior, hypoglycemia awareness, and the Hypoglycemia Fear Survey. Data regarding diabetes, treatment, long-term complications, comorbidity, and complications were obtained for the patients' medical records.
A total of 82% of the subjects were receiving intensive insulin treatment, and the mean HbA1c was 7.8± 1.2%. Mean duration of diabetes was 20± 12 years. The occurrence of SH (including hypoglycemic coma) was 150 episodes/100 patients-years and affected 40.5% of the population. Hypoglycemic coma occurred in 19% of the subjects. SH without coma was independently related to nephopathy, a threshold for hypoglycemic symptoms. and a daily insulin dose 0.1 U/kg higher. Hypoglycemic coma was independently related to neuropathy, B-agents, and alcohol use. The researchers concluded that SH and hypoglycemic coma are common in a nonselected population with type 1 diabetes. The presence of long-term complications, a threshold for symptoms of <3mmol/l, alcohol use, and (nonselective) B-blockers were associated with SH during the previous year. If prospectively confirmed, these results may have consequences for clinical practice.
Finally, the Detroit Free Press reported that research on C-peptide, a hormone, may reduce some of the worst complications of diabetes. Dr. Andres Sims from Wayne State University School of Medicine reported that in the past this hormone was thought to be worthless. Now an international study is expected to begin next year. Current research shows that injections of C-peptide along with insulin reduced complications such as kidney damage. It is known that beta cells make both insulin and C-peptide which are depleted in type 1 diabetes as well as in some cases of type 2 diabetes which are also insulin deficient. Further work to design the study will be done at a meeting in Sweden planned for December, Dr. Sims reported.
